Re: [MBZ] OT: alternative energy - was SMART somethingorother
Odd- Solar power is big out here in the Sonoran desert, and it is reputed to get hot here in the summer- the high today in Phoenix was 112. Of course, that's just warm for us, it will probably get hot in August, though... So how HOT does it get out there in OK? OK Don wrote: Yup - heat is one of the limiting factors for solar cells. They aren't recommended as mainstream energy sources in OK, while wind is. We have lots of both, but it also gets HOT here. ... using semiconductor quantum dots to slow the cooling of hot electrons could produce solar cells with enhanced conversion efficiencies having thermodynamics limits as high as 66%. Note the word "could". That's a mighty big qualifier. Craig -- Lee Einer Dos Manos Jewelry http://www.dosmanosjewelry.com
Re: [MBZ] OT: alternative energy - was SMART somethingorother
Yup - heat is one of the limiting factors for solar cells. They aren't recommended as mainstream energy sources in OK, while wind is. We have lots of both, but it also gets HOT here. > > ... using semiconductor quantum dots to slow the cooling of hot > electrons could produce solar cells with enhanced conversion > efficiencies having thermodynamics limits as high as 66%. > > > Note the word "could". That's a mighty big qualifier. > > > Craig > -- OK Don, KD5NRO Norman, OK '87 300SDL '81 240D '78 450SLC
Re: [MBZ] OT: alternative energy - was SMART somethingorother
On Tue, 21 Jun 2005 16:33:36 -0400 Mitch Haley <[EMAIL PROTECTED]> wrote: > David Brodbeck wrote: > > Yup, and if I remember right, the overall efficiency of sunlight -> PV > > panel -> electrolysis -> compressed hydrogen is only about 30%. The > > whole "hydrogen economy" idea is so easy to poke holes in I'm amazed > > anyone falls for it. > > Q: We've got PV panels over 30%? > > A: I just checked, there are designs with theoretical limits around 60%, > so I guess 30% isn't out of the question any more. Wow. > http://www.nrel.gov/ncpv_prm/adv_concepts.html ... using semiconductor quantum dots to slow the cooling of hot electrons could produce solar cells with enhanced conversion efficiencies having thermodynamics limits as high as 66%. Note the word "could". That's a mighty big qualifier. Craig
Re: [MBZ] OT: alternative energy - was SMART somethingorother
On Tue, 21 Jun 2005, andrew strasfogel wrote: > Solar should NOT be confused with the so-called hydrogen economy. Without solar or some other alternative energy source, the "hydrogen economy" is just a way to move pollution and fossil fuel use around. It doesn't solve anything except maybe smog from tailpipe emissions.
Re: [MBZ] OT: alternative energy - was SMART somethingorother
andrew strasfogel wrote: > > Solar should NOT be confused with the so-called hydrogen economy. Why not? I think of hydrogen as just another kind of battery for storing and transporting electricity.
Re: [MBZ] OT: alternative energy - was SMART somethingorother
Solar should NOT be confused with the so-called hydrogen economy. On 6/21/05, David Brodbeck <[EMAIL PROTECTED]> wrote: > [EMAIL PROTECTED] wrote: > > The problem with sunlight is that the power density at the surface of > > the earth is simply too low for most modern energy uses. I don't > > remember the figures now, but read about studies that looked at the > > power density in watts per square meter at optimum conditions, and > > then figured the area required to produce the same amount of watts as > > found in other sources (i.e. gasoline, nuclear, coal, whatever) and > > even assuming 100% efficiency for the photovoltaic cell, an enormous > > amount of area is required to produce the same amount of power, say > > in 15 gallons of gas. > > Yup, and if I remember right, the overall efficiency of sunlight -> PV > panel -> electrolysis -> compressed hydrogen is only about 30%. The > whole "hydrogen economy" idea is so easy to poke holes in I'm amazed > anyone falls for it. > > ___ > For used parts email [EMAIL PROTECTED] > For new parts see www.buymbparts.com > For repairs see www.oldworldauto.com > > To Unsubscribe or change delivery options go to: > http://striplin.net/mailman/listinfo/mercedes_striplin.net >
Re: [MBZ] OT: alternative energy - was SMART somethingorother
Mitch Haley wrote: David Brodbeck wrote: Yup, and if I remember right, the overall efficiency of sunlight -> PV panel -> electrolysis -> compressed hydrogen is only about 30%. The whole "hydrogen economy" idea is so easy to poke holes in I'm amazed anyone falls for it. Q: We've got PV panels over 30%? I know, I was surprised too. Last I'd heard they were down around 5%.
Re: [MBZ] OT: alternative energy - was SMART somethingorother
David Brodbeck wrote: > Yup, and if I remember right, the overall efficiency of sunlight -> PV > panel -> electrolysis -> compressed hydrogen is only about 30%. The > whole "hydrogen economy" idea is so easy to poke holes in I'm amazed > anyone falls for it. Q: We've got PV panels over 30%? A: I just checked, there are designs with theoretical limits around 60%, so I guess 30% isn't out of the question any more. Wow. http://www.nrel.gov/ncpv_prm/adv_concepts.html
Re: [MBZ] OT: alternative energy - was SMART somethingorother
[EMAIL PROTECTED] wrote: The problem with sunlight is that the power density at the surface of the earth is simply too low for most modern energy uses. I don't remember the figures now, but read about studies that looked at the power density in watts per square meter at optimum conditions, and then figured the area required to produce the same amount of watts as found in other sources (i.e. gasoline, nuclear, coal, whatever) and even assuming 100% efficiency for the photovoltaic cell, an enormous amount of area is required to produce the same amount of power, say in 15 gallons of gas. Yup, and if I remember right, the overall efficiency of sunlight -> PV panel -> electrolysis -> compressed hydrogen is only about 30%. The whole "hydrogen economy" idea is so easy to poke holes in I'm amazed anyone falls for it.
Re: [MBZ] OT: alternative energy - was SMART somethingorother
Once they get the carbon nanotubes to the right length, we can use the space elevator to take the nuke waste up into space, and fire it into the sun. I highly doubt all the waste we can produce in a lifetime will even make a minor blemish in the sun.. The tubes just need to be a couple dozen kilometers long.so far they can do a few microns...hm Jeff Zedic Toronto 87 300TD 83 300D needs engine! (Cheap)
Re: [MBZ] OT: alternative energy - was SMART somethingorother
Back when, I got jazzed about the Solar Power Satellite thing, called up the guy working on the idea at the time (not quite the inventor, but he took the idea and started working it) and got a job working for him. Did some analyses, and it could actually work quite well, except that a rather large area would be required for receiving antennas (rectifying antennas - rectennas they were called) because you would need to keep the power densities of the microwave beams (lasers could work too, but less efficient) low enough not to fry things that flew through them (birds and airplanes mostly) and you would need to size them for few gigawatts to make the numbers work. But there is a lot of dis/un-used land that would be OK to site them on with minimal affects, transmission to load centers would then be an issue. But the overall efficiency of the transmission is quite high (90% or better if I recall), and with improvements in solar cells on the satellites or another conversion means (solar cells were about the cheapest and least difficult to deal with) the whole deal could deliver clean power just about anywhere at reasonable cost. The biggest issue was launching to orbit, but even that had some interesting options that could really lower the cost to orbit from the earth's surface. Building stuff (sheet aluminum to make the structure and solar cells in rolls) on the moon and pushing it earth orbit looked to be the easiest actually, using adequate resources on the moon (aluminum and silicon and vacuum and lots of clean power) and the low energy to get from there to earth orbit. The moon would actually not be too bad a place to do the manufacturing, what with evidence of water there now and advances in automation, and a replicating base could be established with not too much stuff having to be sent there. But even now with $50 or $60/bbl oil, the economics (ansd $ are the best least common denominator for assessing options) probably still favor oil and nukes. And even back then there were people squawking that this approach would have huge negative effects, etc. though they could not really justify that opinion with any sort of rational argument. --R [EMAIL PROTECTED] wrote: Andrew wrote: My dream is that technological breakthroughs will lead to ever more clever ways to harness the power of the sun (photovoltaics), foster energy conservation, and reduce emissions from the use of fossil fuels. There are even some intriguing developments in nuclear power that were unforeseeable a decade ago. The problem with sunlight is that the power density at the surface of the earth is simply too low for most modern energy uses. I don't remember the figures now, but read about studies that looked at the power density in watts per square meter at optimum conditions, and then figured the area required to produce the same amount of watts as found in other sources (i.e. gasoline, nuclear, coal, whatever) and even assuming 100% efficiency for the photovoltaic cell, an enormous amount of area is required to produce the same amount of power, say in 15 gallons of gas. It's really simply a matter of physics. If you then look at the amount of energy required to make the solar cells, and the industrial waste generated, throw in a few cloudy days, and the picture looks worse and worse. What I found to be really exciting is the idea of putting those solar cells in orbit to cut the atmospheric losses, and beaming the energy down in the form of microwaves or a laser or somesuch (concept was proven in Canada a few years back using a high altitude solar powered UAV to stay airborne for weeks at a time while beaming down microwaves). Or build the 'space elevator' and transmit the electricity down the cable. Now we just need to kick NASA to the curb and let the free market take over space exploration/exploitation and we'll have some real fun! Very respectfully, /s/ LCDR Meade M. Dillon, USNR ’85 300TD 320k miles (Euro 5spd) '96 Infiniti I30 147k miles (wife's 5spd) '73 Balboa 20 'Sanctification' Charleston SC "Most men would rather die, than think. Many do." Bertrand Russell ___ For used parts email [EMAIL PROTECTED] For new parts see www.buymbparts.com For repairs see www.oldworldauto.com To Unsubscribe or change delivery options go to: http://striplin.net/mailman/listinfo/mercedes_striplin.net
